Abstract
Drilling fluid is the life line of safe and economic drilling operation to explore oil and gas resources from the earth's crust. However, it is also the root cause of various mud related drilling problems such as shale-drilling fluid interactions, borehole instability, loss of circulation, differential pipe sticking, etc. Differential sticking is one of major drilling problems that is very common when passing through a sticking prone high permeable zone. It is one of the major items of non-productive time that increases the total drilling cost dramatically, especially if there is a delay in recovering a stuck pipe. Moreover, delay or inability in recovering a stuck pipe may lead to other drilling problems leading to abandonment or side tracking of a well. Hence, every step should be taken to recover a stuck pipe as soon as possible.
One of the most effective strategy for quick recovery of a stuck pipe is the use of a highly efficient and rapidly acting spotting fluid to damage, degrade and destroy mudcake-pipe sticking bonds as quickly as possible to release the stuck pipe easily from the mudcake matrix. This dictates quick laboratory evaluation of various spotting fluids available to identify the best spotting fluid for a particular mud and mudcake composition. As the chemistry of the mud additives and the deposited mudcake materials influence the performance of a spotting fluid, it is highly recommended to evaluate the de-bonding, degrading and destructive potential of a spotting fluid for a particular mudcake composition to select the superior and reject the inferior. However, there is no API or any other industry method that can be used for quick screening of various spotting fluids available to the industry to select the most efficient one for a particular stuck pipe rescue operation. This paper describes a dedicated operating software driven novel laboratory method for quick screening and reliable prediction of the performance of various spotting fluids to demonstrate the suitability of the method and test apparatus for oil and gas field application.
Experimental results indicate that the newly developed method and test apparatus can consistently and precisely predict the performance of various spotting fluids and mudcake compositions to select the most suitable spotting fluid for a particular rescue operation. It provides useful guidelines and a practical decision making tool for the drilling and mud engineers and the consultants for quick and easy recovery of stuck pipe from the mudcake matrix.
The method and apparatus will also play an important role in the development of a new generation of high performance spotting fluids to overcome current and future challenges associated with differential pipe sticking problems.
